Field of the Disclosure
The present disclosure relates to a method for fixing a resin tube to a die and a manufacturing method for a resin-tube covered roller.
Description of the Related Art
A fixing device for use in an image forming apparatus using electrophotography generally employs a roller obtained by covering a peripheral surface of a roller part, which is composed of a base formed of metal or heat-resistant resin and a single or multiple heat-resistant elastic layers stacked on the base and formed of, for example, silicone rubber, with a resin tube formed of resin such as fluorine resin (hereinafter referred to as “resin-tube covered roller”).
The resin-tube covered roller can be manufactured by inserting a resin tube into a cylindrical die, folding back and fixing end portions of the resin tube protruding from both end portions of the die to the die, and pouring and curing rubber inside the die in which the resin tube is inserted.
As such a method for folding back the resin tube, Japanese Utility Model Registration Laid-Open No. 03-095212 describes a method for folding back end portions of a resin tube disposed inside a die by expanding the diameter of the end portions of the resin tube by a plurality of diameter expanding claws and advancing the diameter expanding claws along an outer peripheral surface of the die toward the center portion of the die in the diameter expanded state.
However, in the folding method described in Japanese Utility Model Registration Laid-Open No. 03-095212, the resin tube is pulled by the diameter expanding claws. Hence, a thin portion is formed in the resin tube, and distal ends of the diameter expanding claws sometimes break through the thin portion.
To address such a problem, Japanese Patent Laid-Open No. 05-212784 describes a method for folding back end portions of a resin tube by using expanding claws having rollers in their respective distal end portions. In this method, the resin tube is folded back onto outer peripheries of end portions of a pipe by advancing the expanding claws while rolling the rollers in contact with an inner surface of each end portion of the resin tube.